(i) Field of the Invention
This invention relates to a process for selectively removing benzene from gasoline.
(ii) Description of the Prior Art
At the present time, there is environmental pressure to remove benzene, a suspected carcinogen, from gasoline. Technologies, e.g., liquid-liquid extraction or conventional hydrogenation, are presently available. However, the former may be too expensive for low quantities of benzene, and the latter may eliminate all the aromatic components, with significant loss of octane number.
In the patent literature, U.S. Pat. No. 3,767,720 describes the hydrogenation of a pure stream of liquid aromatic in the presence of an aqueous stream of reduced Group VIII cations, including ruthenium. Such process is carried out under the condition of high pH and in the presence of a reducing agent in the aqueous phase to convert the Group VIII cations to neutral species. The source of the Group VIII cations is inorganic salts. This provided a process for producing cyclohexane from benzene using a catalyst comprising a reduced cation of a group VIII element, i.e. in an aqueous solution of, e.g. Zn.sup.++, Cr.sup.++, Hg.sup.+, Hg.sup.++, Ni.sup.++, Mo.sup.++, Fe.sup.++, Fe.sup.+++, Co.sup.++, or Cu.sup.+.
U.S. Pat. No. 3,274,272 patented Sep. 20, 1966 by M. Amagasa et al, describes unusual liquid ammonia complexes with pure aromatic components with thermal decomposition of the ammonia, partly to saturate the aromatic component along with aqueous/metallic Group IA metals to reduce the benzene ammonia complex. It provided a process for producing cyclohexane from benzene using an alkali metal or alkaline earth metal dissolved in liquid ammonia in the presence of a decomposing agent.
U.S. Pat. No. 4,271,323 patented Jun. 2, 1981 by Durand et al, indicates that some homogenous catalysts can be used for hydrogenation of benzene as well as other components. It provided a process for hydrogenating benzene in the liquid phase in the presence of a particularly reacted soluble catalyst.